Fundamental is a game of ever changing rules. When your turn begins, you will be losing the round under the current rule for the game. You must play a card to your card collection and/or change the current rule for the game in order to make yourself the current winner of the round at the end of your turn. If you fail to do this, you are eliminated from the round.
There are seven rules available in the game. Each rule revolves around a fundamental number or set of numbers in mathematics. The winning player under the current rule will have played the most digits of pi, the most prime numbers, or some other collection of numbers of Fundamental importance.
Multiple rounds are played until a player has won the first 5 digits of a Fundamental number.
Knowledge of mathematics is not needed to play Fundamental, but knowledge of mathematics will be gained by playing Fundamental.
—description from the publisher